Touch panel system and electronic device

ABSTRACT

In a touch panel system ( 1 ) of the present invention, a stylus pen ( 3 ) produces output that indicates that a quantitative characteristic value is increased from the characteristic value of a previous output by using a waveform that corresponds to an (L+1)-th drive line (DL L+1 ) other than L numbers of drive lines (DL 1  to DL L ) and, meanwhile, produces output that indicates that the quantitative characteristic value is decreased from the characteristic value of the previous output by using a waveform that corresponds to an (L+2)-th drive line (DL L+2 ) other than the L numbers of drive lines (DL 1  to DL L ). A touch panel controller ( 10 ) includes a conversion output unit ( 19 ) that converts and outputs the quantitative characteristic value by using the sum of the initial value of the quantitative characteristic value and the number of outputs × the unit amount of increase or decrease in the waveform that corresponds to the (L+1)-th drive line (DL L+1 ) or in the waveform that corresponds to the (L+2)-th drive line (DL L+2 ).

TECHNICAL FIELD

The present invention relates to a touch panel system and an electronic device that detect the position of the touch of a touch pen on a touch panel which has electrostatic capacitances formed at each intersection of a plurality of first signal lines and a plurality of second signal lines. Specifically, the invention relates to a method for coping with a case where there are many types of information of an electronic pen when a touch pen is configured of an electronic pen that signals can be input into and output from.

BACKGROUND ART

In the related art, there is known, for example, a touch panel system disclosed in PTL 1 as a touch panel system that detects the position of the touch of a touch pen on a touch panel which has electrostatic capacitances formed at each intersection of a plurality of first signal lines and a plurality of second signal lines.

The touch panel system disclosed in PTL 1 includes a plurality of electronic pens, a panel main body that includes a touch face on which a touch operation is performed by the electronic pens and a finger and in which a plurality of transmission electrodes that runs parallel to each other and a plurality of reception electrodes that runs parallel to each other are arranged into a lattice, a transmission unit that applies a drive signal to the transmission electrodes, a reception unit that receives a response signal which is output from the reception electrodes in response to the drive signal applied to the transmission electrodes and outputs detection data for each intersection of the electrodes, and a control unit that detects the position of a touch on the basis of the detection data which is output from the reception unit, in which the transmission unit applies a pen synchronization signal that synchronizes the transmission and reception of a pen identifiable signal between the electronic pens and the reception unit to the transmission electrodes, the electronic pens transmit the pen identifiable signal to the reception electrodes in response to the detection of the pen synchronization signal in the transmission electrodes at the time of a touch operation, and the control unit, on the basis of the pen synchronization signal that the reception unit receives through the reception electrodes, identifies a pointed object on which a touch operation is performed.

According to this configuration, a plurality of electronic pens can be used because each electronic pen transmits the pen identifiable signal to the reception electrodes in response to the detection of the pen synchronization signal from the transmission electrodes at the time of a touch operation and because the control unit, on the basis of the pen synchronization signal that the reception unit receives through the reception electrodes, identifies the electronic pen that performs the touch operation.

When an electronic pen that is provided with additional functions such as a pen pressure sensing function is used as the touch pen, it is necessary to transmit information that the electronic pen obtains to the touch panel controller.

In this case, for example, in the position detecting device disclosed in PTL 2, the electronic pen transmits information to the touch panel controller by using a signal that is configured of a plurality of types of codes which have different code patterns.

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No. 2012-022543 (published on Feb. 2, 2012)

PTL 2: Japanese Unexamined Patent Application Publication No. 2011-164801 (published on Aug. 25, 2011)

SUMMARY OF INVENTION Technical Problem

In such identification methods of PTL 1 and PTL 2, however, a problem arises when there are many types of information that is transmitted from the electronic pen. The number of types of code patterns increases, and, in turn, information has to be transmitted by a code pattern that has many bit digits. Thus, the amount of signals increases, and the identification of signals becomes complicated.

For example, when the electronic pen outputs a quantitative characteristic value such as in the case of representing a pen pressure value with 10 bits, it is necessary to assign 10 types of drive patterns to one electronic pen. In this case, more drive time is required in sequential driving. In parallel driving, a decoding range becomes wide, or it is difficult to increase the number of electronic pens.

The present invention is devised with consideration of the problem in the related art, and an object thereof is to provide a touch panel system and an electronic device that may simply transmit information in a short amount of time when an electronic pen that outputs a quantitative characteristic value having many types of information is used.

Solution to Problem

In order to resolve the problem, according to an aspect of the present invention, there is provided a touch panel system including a touch pen, a touch panel that has electrostatic capacitances formed at each intersection of K (K is an integer greater than or equal to two) numbers of first signal lines and L (L is an integer satisfying L≧K) numbers of second signal lines, and a touch panel controller, in which the touch panel controller outputs drive signals that drive the K numbers of the first signal lines or the L numbers of the second signal lines from a drive unit through L numbers of drive signal lines and receives input of detection signals from the K numbers of the first signal lines or the L numbers of the second signal lines detected by a detecting unit through L numbers of detection signal lines on the basis of a change in charges that is accumulated in the electrostatic capacitances due to the touch pen when the touch pen touches the touch panel, the touch pen is configured of an electronic pen that outputs a quantitative characteristic value, the electronic pen produces output that indicates that the quantitative characteristic value of the electronic pen is increased from the characteristic value of a previous output by using a waveform that corresponds to an (L+1)-th drive signal line other than the L numbers of the drive signal lines and, meanwhile, produces output that indicates that the quantitative characteristic value of the electronic pen is decreased from the characteristic value of the previous output by using a waveform that corresponds to an (L+2)-th drive signal line other than the L numbers of the drive signal lines, and the touch panel controller includes a conversion output unit that converts and outputs the quantitative characteristic value by using the sum of the initial value of the quantitative characteristic value and the number of outputs × the unit amount of increase or decrease in the waveform that corresponds to the (L+1)-th drive signal line or in the waveform that corresponds to the (L+2)-th drive signal line.

The representation of L+1 and L+2 is for representing drive signal lines other than the L numbers or the K numbers of drive signal lines, meaning that the drive signal lines are not actually connected to the touch panel. Thus, when the actual number of connection lines between the touch panel and the touch panel controller is less than L or K, a waveform that corresponds to an arbitrary drive signal line of the non-connected drive signal lines may be used.

In order to resolve the problem, according to another aspect of the present invention, there is provided an electronic device including the above touch panel system.

Advantageous Effects of Invention

According to the aspects of the present invention, the effect of providing a touch panel system and an electronic device that may simply transmit information in a short amount of time when an electronic pen that outputs a quantitative characteristic value having many types of information is used is achieved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a touch panel system in a first embodiment of the present invention and is a block diagram illustrating a configuration of the touch panel system.

FIG. 2 is an interconnect diagram illustrating a configuration of a touch panel disposed in the touch panel system.

FIG. 3 is a circuit diagram illustrating a configuration of a multiplexer that is used to switch a connection between a signal line connected to the touch panel and a drive line connected to a driver and a connection between the signal line and a sense line connected to a sense amplifier.

FIG. 4 is a block diagram illustrating a configuration of a stylus pen in the touch panel system.

FIG. 5 is a timing chart illustrating a basic operation that is performed to synchronize the stylus pen.

FIG. 6(a) is a diagram illustrating an output relationship between the drive line of the driver and the sense line of the sense amplifier in the touch panel controller to the touch panel and the stylus pen, and FIG. 6(b) is a waveform diagram illustrating a synchronization waveform and a touch detection waveform.

FIG. 7(a) is a waveform diagram illustrating a drive waveform, such as a synchronization waveform and a touch detection waveform transmitted from the touch panel controller to the stylus pen, and a low-frequency noise, FIG. 7(b) is a waveform diagram illustrating a state where the drive waveform and the low-frequency noise are superimposed, and FIG. 7(c) is a waveform diagram illustrating a state where the superimposed waveform is reset at reset timings.

FIG. 8 is a diagram illustrating a configuration of a reset circuit provided in a synchronization signal detector circuit of the stylus pen.

FIG. 9(a) is a waveform diagram illustrating an example of a synchronization waveform transmitted from the touch panel controller, FIG. 9(b) is a waveform diagram illustrating an input waveform received by the stylus pen, FIG. 9(c) is a waveform diagram illustrating an internal waveform when a reference potential is set at a reset timing R1 in FIG. 9(b), and FIG. 9(d) is a waveform diagram illustrating an internal waveform when a reference potential is set at a reset timing R2 in FIG. 9(b).

FIG. 10(a) is a waveform diagram illustrating a synchronization waveform that uses the M-sequence code “1110010” which is not Manchester-coded, and FIG. 10(b) is a waveform diagram illustrating a synchronization waveform that uses the Manchester-coded M-sequence code “1110010”.

FIG. 11(a) is a waveform diagram illustrating an example of a synchronization waveform that has a long High period and is transmitted from the touch panel controller, FIG. 11(b) is a waveform diagram illustrating a reset timing R3 of an input waveform received by the stylus pen, and FIG. 11(c) is a waveform diagram illustrating an internal waveform when a reference potential is set at the reset timing R3 in FIG. 11(b).

FIG. 12(a) is a diagram illustrating a synchronization waveform of a pseudorandom sequence that has periodicity, is Manchester-coded, and is transmitted to the stylus pen from the touch panel controller of the touch panel system, and FIG. 12(b) is a waveform diagram illustrating the synchronization waveform and a touch detection waveform.

FIG. 13 is an operation image diagram illustrating a correspondence between a drive operation of the touch panel controller and a drive operation of the stylus pen.

FIGS. 14(a) to 14(c) are diagrams illustrating a specific drive operation in a synchronization signal detection period, a pause period, and a normal drive period illustrated in FIG. 13.

FIG. 15 is a diagram illustrating a relationship between a drive pattern of the driver in the touch panel controller and a drive pattern of a drive circuit in the stylus pen.

FIG. 16 is a diagram illustrating a pen pressure value that is obtained in the stylus pen and a pen pressure value that is represented in the stylus pen having the pen pressure and in the touch panel controller.

FIG. 17 illustrates a touch panel system in a second embodiment of the present invention and is a block diagram illustrating a configuration of the touch panel system.

FIG. 18 is a diagram illustrating a pen pressure value when there is a difference among an actual pen pressure value of the stylus pen, a pen pressure value that is updated and retained in the stylus pen, and a pen pressure value that is represented in the touch panel controller.

FIG. 19 is a diagram illustrating a pen pressure value in the case of increasing or decreasing the unit amount of increase or decrease by providing a continuous increase or decrease changing unit in a unit increase or decrease amount changing unit of a conversion output unit in the touch panel controller.

FIG. 20 is a diagram illustrating an example of a method for adjusting an inner pen pressure value in the stylus pen.

FIG. 21(a) is a waveform diagram illustrating an input waveform of a synchronization signal received by the stylus pen in a touch panel system in a third embodiment of the present invention, and FIG. 21(b) is a waveform diagram illustrating an internal waveform when a reference potential is set at reset timings R1 to R6.

FIG. 22(a) is a waveform diagram illustrating an example of a synchronization waveform transmitted from the touch panel controller, FIG. 22(b) is a waveform diagram illustrating reset timings R7, R7, and R8 of an input waveform received by the stylus pen, and FIG. 22(c) is a waveform diagram illustrating a synchronization waveform when a reference potential is set at the reset timings R7, R7, and R8 illustrated in FIG. 22(b).

FIG. 23 is a timing chart illustrating output waveforms of the touch panel controller in which a fixing period is disposed immediately before a synchronization waveform is output.

FIG. 24(a) is a waveform diagram illustrating an example of a synchronization waveform transmitted from the touch panel controller, FIG. 24(b) is a waveform diagram illustrating reset timings R11, R12, and R13 of an input waveform received by the stylus pen, and FIG. 24(c) is a waveform diagram illustrating a synchronization waveform when a reference potential is set at the reset timings R11, R12, and R13 illustrated in FIG. 24(b).

FIG. 25(a) is a diagram illustrating a method for transmitting a synchronization waveform that is transmitted by drive lines DL₁ to DL_(L) of the driver in the touch panel controller, FIG. 25(b) is a waveform diagram illustrating an input waveform received by the stylus pen, and FIG. 25(c) is a waveform diagram illustrating a synchronization waveform when a reference potential is set after the input waveform is initially reset in the fixing period illustrated in FIG. 25(b).

FIG. 26 is an operation image diagram illustrating a correspondence between a drive operation of the touch panel controller and a drive operation of the stylus pen.

FIG. 27 is a diagram illustrating a specific drive operation in the fixing period illustrated in FIG. 26.

FIG. 28 is a block diagram illustrating a configuration of a mobile phone that is provided with a touch panel system in a fourth embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS First Embodiment

An embodiment of the present invention will be described as follows on the basis of FIG. 1 to FIG. 16.

(Configuration of Touch Panel System)

A configuration of a touch panel system 1 of the present embodiment will be described on the basis of FIG. 1 and FIG. 2. FIG. 1 is a block diagram illustrating a configuration of the touch panel system 1 of the present embodiment, and FIG. 2 is an interconnect diagram illustrating a configuration of a touch panel disposed in the touch panel system.

The touch panel system 1 of the present embodiment, as illustrated in FIG. 1, is provided with a touch panel 2, a stylus pen 3 as a touch pen and an electronic pen, and a touch panel controller 10 that drives the touch panel 2 and the stylus pen 3.

The touch panel 2, as illustrated in FIG. 2, is provided with horizontal signal lines HL₁ to HL_(K) as K (K is a positive integer) numbers first signal lines that are plural lines arranged parallel to each other along the horizontal direction and vertical signal lines VL₁ to VL_(L) as L (L is a positive integer) numbers of second signal lines that are plural lines arranged parallel to each other along the vertical direction. Electrostatic capacitances C11 to CKL are generated at each intersection of the horizontal signal lines HL₁ to HL_(K) and the vertical signal lines VL₁ to VL_(L). While K and L may be either the same or different, the present embodiment will be described on the assumption that L≧K. In addition, while the vertical signal lines VL₁ to VL_(L) vertically intersect the horizontal signal lines HL₁ to HL_(K) in the present embodiment, the present invention is not necessarily limited to this, provided that both intersect each other.

The touch panel 2, although preferably having a width such that a hand holding the stylus pen 3 can be put on the touch panel 2, may have a size used in a smartphone.

The stylus pen 3, in the present embodiment, is not only a touch pen that is configured of a conductor and that is simply used for touching the touch panel 2 but also a pen that signals can be input into and output from. As described below, a synchronization signal detector circuit 36 is disposed in the stylus pen 3 so that a synchronization signal for synchronization with a dedicated synchronization signal generated by a timing generator 14 of the touch panel controller 10 is received and input into the stylus pen 3.

The touch panel controller 10, as illustrated in FIG. 2, is provided with a multiplexer 11, a driver 12, a sense amplifier 13, the timing generator 14, an AD converter 15, capacitance distribution calculating unit 16, a touch recognizing unit 17, and a pen position detecting unit 18.

The driver 12 is configured to apply voltage to drive lines DL₁ to DL_(K) or to drive lines DL₁ to DL_(L) in correspondence with driving of the horizontal signal lines HL₁ to HL_(K) or driving of the vertical signal lines VL₁ to VL_(L) in the touch panel 2.

The sense amplifier 13 reads a signal of initial charges and a linear summation signal through sense lines SL₁ to SL_(L) and supplies the signal and the linear summation signal to the AD converter 15. The initial charges of the signal correspond to each of the electrostatic capacitances C11 to CKL of the touch panel 2 at the time of driving the horizontal signal lines HL₁ to HL_(K) in a first signal line drive period. The linear summation signal corresponds to a first pen charge signal that is charges at the time of a touch which correspond to the electrostatic capacitances between the stylus pen 3 and each of the L numbers of the vertical signal lines VL₁ to VL_(L) at the time of a touch. That is, when the stylus pen 3 approaches a position on the touch panel 2 while charges corresponding to each of the electrostatic capacitances C11 to CKL are detected in the first signal line drive period, charges of the electrostatic capacitance at the position change. Thus, the changed changes of the electrostatic capacitance can be detected as a linear summation signal. Usually, when the stylus pen 3 approaches the touch panel 2, each of the electrostatic capacitances C11 to CKL at the approached position increases.

The sense amplifier 13 is configured to read a signal of initial charges and a linear summation signal through the sense lines SL₁ to SL_(K) and to supply the signal and the linear summation signal to the AD converter 15. The initial charges of the signal correspond to each of the electrostatic capacitances C11 to CKL of the touch panel 2 at the time of driving the vertical signal lines VL₁ to VL_(L) in a second signal line drive period. The linear summation signal corresponds to a second pen charge signal that is charges at the time of a touch which correspond to the electrostatic capacitances between the stylus pen 3 and each of the K numbers of the horizontal signal lines HL₁ to HL_(K) at the time of a touch.

Next, the multiplexer 11 will be described on the basis of FIG. 3. FIG. 3 is a circuit diagram illustrating a configuration of a multiplexer that switches connections between the horizontal signal lines HL₁ to HL_(K) or the vertical signal lines VL₁ to VL_(K) to VL_(L) disposed in the touch panel 2 and the drive lines DL₁ to DL_(K) to DL_(L) connected to the driver or the sense lines SL₁ to SL_(K) to SL_(L) connected to the sense amplifier 13.

The multiplexer 11 is a connection switch circuit that switches connections between a plurality of inputs and a plurality of outputs. In the present embodiment, as illustrated in FIG. 3, the multiplexer 11 switches between a first connection state where the horizontal signal lines HL₁ to HL_(K) are connected to the drive lines DL₁ to DL_(K) of the driver 12 and where the vertical signal lines VL₁ to VL_(K) to VL_(L) are connected to the sense lines SL₁ to SL_(K) to SL_(L) of the sense amplifier 13 and a second connection state where the horizontal signal lines HL₁ to HL_(K) are connected to the sense lines SL₁ to SL_(K) of the sense amplifier 13 and where the vertical signal lines VL₁ to VL_(K) to VL_(L) are connected to the drive lines DL₁ to DL_(K) to DL_(L) of the driver 12.

In the multiplexer 11, when the signal of a control line CL illustrated in FIG. 3 is set to Low, the horizontal signal lines HL₁ to HL_(K) are connected to the drive lines DL₁ to DL_(K), and the vertical signal lines VL₁ to VL_(L) are connected to the sense lines SL₁ to SL_(L). Meanwhile, when the signal of the control line CL is set to High, the horizontal signal lines HL₁ to HL_(K) are connected to the sense lines SL₁ to SL_(K), and the vertical signal lines VL₁ to VL_(L) are connected to the drive lines DL₁ to DL_(L).

Next, the timing generator 14 illustrated in FIG. 1 generates a signal that defines the operation of the driver 12, a signal that defines the operation of the sense amplifier 13, and a signal that defines the operation of the AD converter 15 and respectively supplies the signals to the driver 12, the sense amplifier 13, and the AD converter 15. In addition, the timing generator 14 generates a synchronization signal. The touch panel controller 10 is configured to drive the horizontal signal lines HL₁ to HL_(K) and the vertical signal lines VL₁ to VL_(L) by using the synchronization signal generated by the timing generator 14 as a synchronization-dedicated signal.

Next, the AD converter 15, during the first signal line drive period, performs AD conversion on charges that correspond to each of the electrostatic capacitances C11 to CKL and that are read through the vertical signal lines VL₁ to VL_(L) and through the sense lines SL₁ to SL_(L) and on the linear summation signal that corresponds to the first pen charge signal which is charges corresponding to the electrostatic capacitances between the stylus pen 3 and each of the L numbers of the vertical signal lines VL₁ to VL_(L). The AD converter 15 supplies the AD-converted charges and linear summation signal to the capacitance distribution calculating unit 16.

The AD converter 15, during the second signal line drive period, performs AD conversion on charges that correspond to each of the electrostatic capacitances C11 to CKL and that are read through the horizontal signal lines HL₁ to HL_(K) and through the sense lines SL₁ to SL_(K) and on the linear summation signal that corresponds to the second pen charge signal which is charges corresponding to the electrostatic capacitances between the stylus pen 3 and each of the K numbers of the horizontal signal lines HL₁ to HL_(K). The AD converter 15 supplies the AD-converted charges and linear summation signal to the capacitance distribution calculating unit 16.

Next, the capacitance distribution calculating unit 16, on the basis of the linear summation signal that includes the first pen charge signal and the second pen charge signal and on the basis of a code sequence based on driving, calculates the distribution of electrostatic capacitances on the touch panel 2, the distribution of electrostatic capacitances between the stylus pen 3 and each of the L numbers of the vertical signal lines VL₁ to VL_(L), and the distribution of electrostatic capacitances between the stylus pen 3 and each of the K numbers of the horizontal signal lines HL₁ to HL_(K), supplies the distribution of electrostatic capacitances on the touch panel 2 to the touch recognizing unit 17, and supplies the distribution of electrostatic capacitances between the stylus pen 3 and each of the L numbers of the vertical signal lines VL₁ to VL_(L) and the distribution of electrostatic capacitances between the stylus pen 3 and the K numbers of the horizontal signal lines HL₁ to HL_(K) to the pen position detecting unit 18 that is position detecting means. The touch recognizing unit 17 recognizes the position of a touch on the touch panel 2 on the basis of the distribution of electrostatic capacitances supplied from the capacitance distribution calculating unit 16.

The pen position detecting unit 18 detects the position of the stylus pen 3 along the horizontal signal lines on the basis of the distribution of electrostatic capacitances between the stylus pen 3 and each of the L numbers of the vertical signal lines VL₁ to VL_(L). In addition, the pen position detecting unit 18 detects the position of the stylus pen 3 along the vertical signal lines on the basis of the distribution of electrostatic capacitances between the stylus pen 3 and each of the K numbers of the horizontal signal lines HL₁ to HL_(K).

(Detection Operation for Detecting Position of Touch of Touch Pen)

A detection operation for detecting the position of a touch of the stylus pen 3 in the touch panel system 1 having the above configuration will be described in a temporal manner below. Here, the detection operation will be described in a case where the stylus pen 3 is simply used as a touch pen.

First, in the first signal line drive period, in the first connection state where the horizontal signal lines HL₁ to HL_(K) are connected to the drive lines DL₁ to DL_(K) of the driver 12 and where the vertical signal lines VL₁ to VL_(L) are connected to the sense lines SL₁ to SL_(L) of the sense amplifier 13, the driver 12 drives the horizontal signal lines HL₁ to HL_(K) by applying voltage to the drive lines DL₁ to DL_(K).

Then, in the first signal line drive period, charges that are accumulated in each of the electrostatic capacitances C11 to CKL by driving the horizontal signal lines HL₁ to HL_(K) and L numbers of first linear summation signals that are based on the first pen charge signal which is charges corresponding to the electrostatic capacitances between the stylus pen 3 and each of the L numbers of vertical signal lines VL₁ to VL_(L) at the time of the approach of the stylus pen 3 to the touch panel 2 are output from each of the L numbers of the vertical signal lines VL₁ to VL_(L).

The sense amplifier 13 reads the L numbers of the first linear summation signals that include the first pen charge signal through the multiplexer 11 and through the sense lines SL₁ to SL_(L) and supplies the L numbers of the first linear summation signals to the AD converter 15. The AD converter 15 performs AD conversion on the L numbers of the first linear summation signals that include the first pen charge signal and outputs the AD-converted L numbers of the first linear summation signals to the capacitance distribution calculating unit 16.

Next, the first connection state is switched to the second connection state so as to change the drive signal and the sense signal of the horizontal signal lines HL₁ to HL_(K) and the vertical signal lines VL₁ to VL_(L). That is, in the second connections state, the horizontal signal lines HL₁ to HL_(K) are connected to the sense lines SL₁ to SL_(K) of the sense amplifier 13, and the vertical signal lines VL₁ to VL_(L) are connected to the drive lines DL₁ to DL_(L) of the driver 12.

The driver 12, afterward, drives the vertical signal lines VL₁ to VL_(L) by applying voltage to the drive lines DL₁ to DL_(L).

Then, in the second signal line drive period, charges that are accumulated in each of the electrostatic capacitances C11 to CKL by driving the vertical signal lines VL₁ to VL_(L) and K numbers of second linear summation signals that are based on the second pen charge signal which is charges corresponding to the electrostatic capacitances between the stylus pen 3 and each of the K numbers of the horizontal signal lines HL₁ to HL_(K) are output from each of the K numbers of the horizontal signal lines HL₁ to HL_(K). At this time, the sense amplifier 13 reads the K numbers of the second linear summation signals that include the second pen charge signal through the multiplexer 11 and through the sense lines SL₁ to SL_(K) and supplies the K numbers of the second linear summation signals to the AD converter 15. The AD converter 15 performs AD conversion on the K numbers of the second linear summation signals that include the second pen charge signal and outputs the AD-converted K numbers of the second linear summation signals to the capacitance distribution calculating unit 16.

Next, in a position detecting process, the capacitance distribution calculating unit 16 calculates the distribution of electrostatic capacitances on the touch panel 2 and supplies the first linear summation signals that include the first pen charge signal, the second linear summation signals that include the second pen charge signal, and the distribution of electrostatic capacitances to the touch recognizing unit 17. The capacitance distribution calculating unit 16 calculates the position of the stylus pen 3 along the horizontal signal lines and the position of the stylus pen 3 along the vertical signal lines and supplies the positions of the stylus pen 3 to the pen position detecting unit 18.

The touch recognizing unit 17, afterward, recognizes the position of a touch on the touch panel 2 on the basis of the distribution of electrostatic capacitances supplied from the capacitance distribution calculating unit 16.

The pen position detecting unit 18 detects the position of the stylus pen 3 on the touch panel 2 on the basis of the position of the stylus pen 3 along the horizontal signal lines and the position of the stylus pen 3 along the vertical signal lines calculated by the capacitance distribution calculating unit 16.

In the above description, in the present embodiment, both the horizontal signal lines HL₁ to HL_(K) and the vertical signal lines VL₁ to VL_(L) are driven in a parallel and simultaneous manner. That is, parallel driving is performed. However, not necessarily limited to this, driving of the K numbers of the horizontal signal lines HL₁ to HL_(K) and driving of the L numbers of the vertical signal lines VL₁ to VL_(L) in the touch panel 2 may be either parallel driving or sequential driving. Parallel driving means that the K numbers of the horizontal signal lines HL₁ to HL_(K) or the L numbers of the vertical signal lines VL₁ to VL_(L) are driven in a parallel and simultaneous manner, and sequential driving means that the K numbers of the horizontal signal lines HL₁ to HL_(K) or the L numbers of the vertical signal lines VL₁ to VL_(L) are sequentially driven in order from the horizontal signal line HL₁ or from the vertical signal line VL₁. Parallel driving is preferable in terms of speed, and the present embodiment uses parallel driving.

As such, the touch panel system 1 of the present embodiment is provided with the touch panel 2 that has electrostatic capacitances formed at each intersection of the plurality of first signal lines and the plurality of second signal lines, the touch pen, and the touch panel controller 10. The touch panel controller 10, when repeatedly switching driving such that the horizontal signal lines HL₁ to HL_(K) that are the plurality of first signal lines are driven to output charge signals based on each electrostatic capacitance from each of the vertical signal lines VL₁ to VL_(L) that are the second signal lines during the first signal line drive period and such that the vertical signal lines VL₁ to VL_(L) that are the plurality of second signal lines are driven to output charge signals based on each electrostatic capacitance from each of the horizontal signal lines HL₁ to HL_(K) that are the first signal lines during the second signal line drive period, detects the position of a touch on the basis of a change in charges of the electrostatic capacitances due to the touch pen when the touch pen touches the touch panel 2.

In the touch pen coordinate position detecting method in the touch panel system 1 having the above configuration, when the touch pen touches the touch panel 2, a detected position in the first signal line drive period and a detected position in the second signal line drive period are represented at the same position. Meanwhile, an erroneous signal due to phantom noise that is caused by the touch of a hand, a finger, and the like of a human body, which receives electromagnetic noise, on the touch panel 2, even when represented in the first signal line drive period by switching the first signal lines and the second signal lines, is not represented at the same position in the second signal line drive period. Therefore, by determining a detected position with a logical product of a detected position in the first signal line drive period and a detected position in the second signal line drive period, it is possible to distinguish a signal of a touch of the touch pen and an erroneous signal due to phantom noise and to remove the erroneous signal due to phantom noise.

Phantom noise is a noise that generates a detection signal based on static electricity at a position different from the position of a touch of the touch pen through a hand which holds the touch pen. Since the position where the detection signal is generated is different from the valid position of a touch of the touch pen, the detection signal is regarded as noise.

(Configuration of Stylus Pen and Pen Pressure Sensing Function)

The stylus pen 3 of the present embodiment includes a pen pressure sensor that is used to detect a pen pressure level which is a quantitative characteristic value. A configuration of the stylus pen 3 will be described on the basis of FIG. 4. FIG. 4 is a sectional view illustrating a configuration of the stylus pen 3.

The stylus pen 3, as illustrated in FIG. 4, includes a pen main body 30 that a user holds with the hand thereof and that includes a conductive holding portion 30 a which is formed into a substantially cylindrical shape so that the user can hold with the hand thereof. A pen tip portion 31 that is pressed to the touch panel 2 at the time of a touch operation is disposed at the tip end of the pen main body 30.

The pen tip portion 31 includes a pen tip cover 31 a, a pen tip axis 31 b, insulators 31 c and 31 c that hold the pen tip cover 31 a in a manner capable of moving the pen tip cover 31 a forward in the axial direction, and a pen pressure sensor 31 d that is disposed on the deep side of the pen tip axis 31 b.

The pen tip cover 31 a is made of insulating material, and the pen tip axis 31 b is made of conductive material such as metal or conductive synthetic resin material.

The pen pressure sensor 31 d is configured of, for example, a semiconductor piezoresistive pressure sensor in which a semiconductor strain gauge is formed on the surface of an unillustrated diaphragm. Therefore, when the pen tip cover 31 a of the pen tip portion 31 is pressed to the touch panel 2 at the time of a touch operation, the pen tip axis 31 b is pushed through the pen tip cover 31 a and presses the surface of the diaphragm of the pen pressure sensor 31 d. Accordingly, a change in electrical resistance due to a piezoresistive effect that is generated by the deformation of the diaphragm is converted into an electrical signal. Accordingly, the pressure of the stylus pen 3 can be detected. A principle of detecting the pressure of a pen is not necessarily limited to this. Other principles of detection can be used.

Disposed in the pen main body 30 are a connection switch 32, a controller circuit 33, operation changing switches 34 a and 34 b, a sense circuit 35, the synchronization signal detector circuit 36, a timing adjuster circuit 37, and a drive circuit 38. The connection switch 32 may be omitted. When the connection switch 32 is omitted, the output of the controller circuit 33 is connected to the pen tip axis 31 b.

The connection switch 32 is an electronic switch that is configured of a field-effect transistor (FET) or the like and is controlled in an ON-OFF manner by the controller circuit 33. When the connection switch 32 is OFF, the pen tip cover 31 a is electrically disconnected from the holding portion 30 a of the pen main body 30. At this time, since the component capacitance of the pen tip portion 31 is very small, the touch panel system 1 does not recognize approaching or abutting of the stylus pen 3 even when the pen tip cover 31 a approaches the touch panel 2.

Meanwhile, when the connection switch 32 is ON, the pen tip cover 31 a is electrically connected to the holding portion 30 a of the pen main body 30 through the pen tip axis 31 b, and a human body is conducted to the pen tip cover 31 a through the holding portion 30 a. Accordingly, since a human body has a comparatively large electrostatic capacitance, when the stylus pen 3 approaches or touches the touch panel 2, charges accumulated in each of the electrostatic capacitances C11 to CKL of the touch panel 2 change, and the touch panel system 1 can detect the state of the touch of the stylus pen 3.

Disposed in the stylus pen 3 are, for example, a push-type first operating switch 39 a and a push-type second operating switch 39 b. Functions assigned to the first operating switch 39 a and the second operating switch 39 b are performed through the controller circuit 33 by pushing the first operating switch 39 a and the second operating switch 39 b. Examples of a function assigned to the first operating switch 39 a can include an eraser function. The first operating switch 39 a can turn ON or OFF the eraser function. In addition, examples of a function assigned to the second operating switch 39 b can include a mouse right-clicking function. The second operating switch 39 b can turn ON or OFF the mouse right-clicking function.

The eraser function and the mouse right-clicking function are merely an example. The functions of the first operating switch 39 a and the second operating switch 39 b are not limited to the eraser function and the mouse right-clicking function. It is also possible to further dispose other operating switches to add other functions.

A signal of a touch of the stylus pen 3 on the touch panel 2, that is, the first pen charge signal and the second pen charge signal indicating the position of a touch are detected by switching driving of the horizontal signal lines HL₁ to HL_(K) and the vertical signal lines VL₁ to VL_(L) as described above when the stylus pen 3 touches the touch panel 2 in a state where the connection switch 32 of the stylus pen 3 is ON.

In order to detect a detection signal of the pen pressure of the pen tip portion 31 in the stylus pen 3, the present embodiment uses a method that matches the drive pattern of the drive circuit 38 of the stylus pen 3 to the drive pattern of the horizontal signal lines HL_(K+1) and HL_(K+2) (or later one) of the touch panel 2 driven by the touch panel controller 10, that is, to the drive pattern of the (K+1)-th and (K+2)-th (or later) drive lines DL_(K+1) and DL_(K+2) (or later one) of the driver 12 in the first signal line drive period and matches the drive pattern of the drive circuit 38 to the drive pattern of the vertical signal lines VL_(L+1) and VL_(L+2) (or later one) of the touch panel 2 driven by the touch panel controller 10, that is, to the drive pattern of the (L+1)-th and (L+2)-th (or later) drive lines DL_(L+1) and DL_(L+2) (or later one) of the driver 12 in the second signal line drive period. Here, the horizontal signal lines HL_(K+1) and HL_(K+2) (or later one) and the vertical signal lines VL_(L+1) and VL_(L+2) (or later one) do not actually exist. In FIG. 1 and FIG. 2, although drive patterns may be different depending on the drive periods like the drive line DL_(K+1) and the drive line DL_(L+1) (K≠L), illustration is provided with a phantom line using the representation of the drive lines DL_(L+1) and DL_(L+2) for convenience of representation. The representation of the drive lines DL_(L+1) and DL_(L+2) will also be used in later descriptions.

Accordingly, in the touch panel controller 10, an increasing or decreasing signal of the pen pressure sensor 31 d in the stylus pen 3 can be obtained through the sense lines SL₁ to SL_(L) by waveforms that correspond to the drive lines DL_(L+1) and DL_(L+2). That is, in the present embodiment, by the waveforms that correspond to the drive lines DL_(L+1) and DL_(L+2), an increasing or decreasing signal of the pen pressure sensor 31 d in the stylus pen 3 is output, and the signal is detected by the sense lines SL₁ to SL_(L) through the horizontal signal lines HL₁ to HL_(K) or through the vertical signal lines VL₁ to VL_(L) that pass through the position of a touch on the touch panel 2 at that time.

As a consequence, the controller circuit 33 of the stylus pen 3 generates pen pressure information on the basis of the output of the pen pressure sensor 31 d, and the pen pressure information is output to the touch panel controller 10 by the waveforms that correspond to the drive lines DL_(L+1) and DL_(L+2) in response to a transmission instruction from the controller circuit 33. A specific method for the output of the pen pressure sensor 31 d will be described later.

(Basic Operation of Synchronization of Touch Panel Controller and Stylus Pen)

The stylus pen 3 of the present embodiment wirelessly transmits and receives signals with the touch panel controller 10. Therefore, the pen tip portion 31 is driven with the same pattern as driving the drive line DL_(L+1) or DL_(L+2) in accordance with the timing of driving the drive lines DL₁ to DL_(L) in the touch panel controller 10. Therefore, the drive circuit 38 is disposed in the stylus pen 3 so that the stylus pen 3 can be driven in the same manner as the driver 12 of the touch panel controller 10.

Driving of the drive lines DL₁ to DL_(L) in the touch panel controller 10 is based on a drive timing that is generated by the timing generator 14. Thus, the stylus pen 3 has to operate in synchronization with the timing when the touch panel controller 10 is driven. Therefore, by disposing the sense circuit 35, the synchronization signal detector circuit 36, and the timing adjuster circuit 37 in the stylus pen 3 of the present embodiment, the dedicated synchronization signal that the touch panel controller 10 drives is detected in the stylus pen 3, and the timing of the dedicated synchronization signal of the touch panel controller 10 is matched to the timing of a pen synchronization signal that is generated by the timing adjuster circuit 37 of the stylus pen 3.

A basic principle of the synchronization of the stylus pen 3 in the touch panel system 1 will be described on the basis of FIG. 5. FIG. 5 is a timing chart illustrating the basic principle of synchronization.

The stylus pen 3 detects the dedicated synchronization signal generated by the timing generator 14 of the touch panel controller 10 with the sense circuit 35 and the synchronization signal detector circuit 36. The dedicated synchronization signal is assumed to be a single pulse for simplification.

As illustrated in FIG. 6, it is assumed that a touch panel synchronization signal SO that is the dedicated synchronization signal configured of a single pulse is generated in a constant cycle.

The sense circuit 35 of the stylus pen 3 generates a plurality of synchronization signal candidates S1 to Sp (p is an integer greater than or equal to two). The synchronization signal candidate Sp illustrated in FIG. 5 represents a signal that is delayed by approximately one cycle from the synchronization signal candidate S1. The stylus pen 3 selects a synchronization signal that has a high degree of matching with the dedicated synchronization signal transmitted from the timing generator 14 of the touch panel controller 10 from the synchronization signal candidates S1 to Sp and uses the synchronization signal as a synchronization signal for communication with the touch panel controller 10. In the example illustrated in FIG. 5, the synchronization signal candidate S4 or S5 that has a high degree of matching with the touch panel synchronization signal S0 is used as the pen synchronization signal of the stylus pen 3.

The stylus pen 3 is in a detection mode until being synchronized, and the drive circuit 38 is not driven.

According to such a principle, the stylus pen 3 can synchronize with the dedicated synchronization signal of the touch panel controller 10.

(Synchronization Operation of Touch Panel Controller and Stylus Pen of Present Embodiment)

In actuality, synchronization is not easy because noise exists in the reception of the dedicated synchronization signal from the touch panel controller 10. Specifically, since a low-frequency component is superimposed on the dedicated synchronization signal, it is difficult to correctly obtain the amplitude of the pulse of the dedicated synchronization signal. As a consequence, a problem arises in that the pulse of the dedicated synchronization signal may not be captured.

An example of a method for resolving such a problem will be described on the basis of FIG. 6(a) to FIG. 12(c). FIG. 6(a) is a diagram illustrating an output relationship between the drive line of the driver and the sense line of the sense amplifier in the touch panel controller to the touch panel and the stylus pen, and FIG. 6(b) is a waveform diagram illustrating a synchronization waveform and a touch detection waveform. FIG. 7(a) is a waveform diagram illustrating a drive waveform, such as a synchronization waveform and a touch detection waveform transmitted from the touch panel controller to the stylus pen, and a low-frequency noise, FIG. 7(b) is a waveform diagram illustrating a state where the drive waveform and the low-frequency noise are superimposed, and FIG. 7(c) is a waveform diagram illustrating a state where the superimposed waveform is reset at reset timings. FIG. 8 is a diagram illustrating a configuration of a reset circuit disposed in the synchronization signal detector circuit of the stylus pen. FIG. 9(a) is a waveform diagram illustrating an example of a synchronization waveform transmitted from the touch panel controller, FIG. 9(b) is a waveform diagram illustrating an input waveform received by the stylus pen, FIG. 9(c) is a waveform diagram illustrating an internal waveform when a reference potential is set at a reset timing R1 in FIG. 9(b), and FIG. 9(d) is a waveform diagram illustrating an internal waveform when a reference potential is set at a reset timing R2 in FIG. 9(b). FIG. 10(a) is a waveform diagram illustrating a synchronization waveform that uses the M-sequence code “1110010” which is not Manchester-coded, and FIG. 10(b) is a waveform diagram illustrating a synchronization waveform that uses the Manchester-coded M-sequence code “1110010”. FIG. 11(a) is a waveform diagram illustrating an example of a synchronization waveform that has a long High period and is transmitted from the touch panel controller, FIG. 11(b) is a waveform diagram illustrating a reset timing R3 of an input waveform received by the stylus pen, and FIG. 11(c) is a waveform diagram illustrating an internal waveform when a reference potential is set at the reset timing R3 in FIG. 11(b). FIG. 12(a) is a diagram illustrating a synchronization waveform of a pseudorandom sequence that has periodicity, is Manchester-coded, and is transmitted to the stylus pen from the touch panel controller of the touch panel system, and FIG. 12(b) is a waveform diagram illustrating the synchronization waveform and a touch detection waveform.

In the touch panel system 1 of the present embodiment, as illustrated in FIG. 6(a), the dedicated synchronization signal of the touch panel controller 10 is created in the timing generator 14 of the touch panel controller 10 and is transmitted by the driver 12 using the drive lines DL₁ to DL_(L). As a mechanism that notifies the stylus pen 3 of the dedicated synchronization signal which is the drive timing of the touch panel controller 10, as illustrated in FIG. 6(b), the drive lines DL₁ to DL_(L) are driven by a waveform that represents synchronization separately from a normal touch detection waveform. Specifically, the touch detection waveform is generated after the synchronization waveform is generated in each of the drive lines DL₁ to DL_(L). For easy understanding of description, the touch detection waveform is generated by sequential driving. In addition, representing the generation of the synchronization waveform with a plurality of continuous pulses is to facilitate distinguishing the appearance of the synchronization waveform from the waveform of sequential driving. In actuality, a waveform obtained by Manchester-coding the M-sequence code suggested in the present embodiment or the like is more likely to be detected as a synchronization waveform.

Various types of noise, particularly low-frequency noise, are mixed into the waveform of a signal received by the stylus pen 3. In FIG. 7(a), it is assumed that a wide straight line illustrates the dedicated synchronization waveform that is configured of a plurality of dense pulses which the touch panel controller 10 drives and that a sin curve illustrates noise.

The waveform of the signal received by the stylus pen 3 is configured of the superimposition of the synchronization waveform obtained from the touch panel controller 10 and low-frequency noise as illustrated in FIG. 7(b). As a consequence, in the waveform of the signal received by the stylus pen 3, the amplitude of low-frequency noise is larger than the amplitude of the synchronization waveform obtained from the touch panel controller 10. Thus, when using the waveform of the received signal from the minimum potential to the maximum potential thereof, it is difficult to obtain the synchronization waveform signal because the amplitude of the synchronization waveform signal is a relatively minute amplitude in comparison with the noise.

Therefore, as a method for finding the synchronization waveform from the waveform illustrated in FIG. 7(b) in which the synchronization waveform and low-frequency noise are superimposed, for example, there are a method of removing low-frequency noise with a low frequency cut-off filter and a method of performing a reset operation that sets a reference potential for the waveform in which the synchronization waveform and low-frequency noise are superimposed and obtaining the amplitude of an internal waveform by using the potential difference from the reference potential. However, low frequency cut-off filters are expensive.

In the present embodiment, thus, the stylus pen 3 that is on the reception side of the synchronization waveform uses the method of performing a reset operation that sets a reference potential for the received input waveform and obtaining the amplitude of an internal waveform by using the potential difference from the reference potential. However, the present invention is not necessarily limited to this. It is also possible to remove noise that is configured of low-frequency components by using a low frequency cut-off filter.

In the present embodiment, the synchronization signal detector circuit 36 of the stylus pen 3 is provided with a reset circuit 36 a illustrated in FIG. 8 so as to perform a reset operation that sets a reference potential for the received input waveform. The reset circuit 36 a resets the superimposed signal waveform illustrated in FIG. 7(b) in which the synchronization waveform obtained from the touch panel controller 10 and low-frequency noise are superimposed. By resetting the superimposed signal waveform, the superimposed signal waveform returns to the reference potential at a reset timing as illustrated in FIG. 7(c). That is, the reference potential is set to the same potential as the input signal. Then, a positive potential is output when the potential of the superimposed signal waveform input is higher than the reference potential, while a negative potential is output when the potential of the superimposed signal waveform input is lower than the reference potential. Accordingly, it is possible to remove low-frequency components and to keep the amplitude of the signal within a certain range.

When a reset operation that sets a reference potential for the received input waveform is performed on the synchronization waveform that is obtained from the touch panel controller 10 and that is represented by a sequence of a plurality of equidistant pulses, a problem arises in that it is difficult to identify the dedicated synchronization signal that is the drive timing of the touch panel controller 10 because pulses are not captured when the reset timing that sets a reference potential for the reception-side stylus pen 3 overlaps with the pulses of the synchronization waveform.

When, for example, the synchronization waveform illustrated in FIG. 9(a) is transmitted from the touch panel controller 10, an input waveform in the reception-side stylus pen 3 is illustrated by the waveform of FIG. 9(b). At this time, the internal waveform when the reference potential is set at the reset timing R1 in the waveform of FIG. 9(b) is illustrated in FIG. 9(c). However, when the reset timing R2 is set to the second pulse in the waveform of FIG. 9(b), the internal waveform when the reference potential is set is as illustrated in FIG. 9(d). As a consequence, since the second pulse does not have a positive rise, the second pulse is not captured. That is, it is difficult to identify the dedicated synchronization signal that is the drive timing of the touch panel controller 10.

The present embodiment, therefore, uses a constant pattern synchronization signal that is configured of a pseudorandom sequence having periodicity as a synchronization waveform that is transmitted by the touch panel controller 10. Specifically, an M-sequence code or a Gold sequence code is used.

The pseudorandom sequence is a code sequence that is used in a pseudorandom signal which is an artificially created random signal. That is, while actual random signals existing in nature are usually called a random signal, artificially created random signals are called a pseudorandom signal. Although a certain rule is necessary since the pseudorandom signal is artificially created, various considerations are made to make the statistical properties of the created signal as close as possible to the statistical properties of the actual random signal. Usually, considerations are made to make the autocorrelation function of the created signal as close as possible to the autocorrelation function δ(t) of white noise. The pseudorandom signal is created by associating a pseudorandom sequence (a sequence of numbers) with physical quantities such as voltage. Types of pseudorandom sequences include a finite length sequence and a periodic sequence. Periodic sequences are widely used in terms of ease of generation and usage. There are an M-sequence and a Gold sequence that represent the periodic sequence.

The autocorrelation of an M-sequence signal and a Gold sequence code shows a very sharp peak and has properties such that the correlation values with others except for the M-sequence signal and the Gold sequence code are very small. The M-sequence and the Gold sequence are sequences that are configured of binary numbers of zero and one and that have periodicity in which binary sequences are connected.

The reliability of determining synchronization is increased by using the M-sequence code or Gold sequence code as a synchronization waveform transmitted by the touch panel controller 10 even when the reset timing overlaps with one pulse because pulses that match the M-sequence code are determined as a correct synchronization timing.

When, for example, the M-sequence code “1110010” is used as illustrated in FIG. 10(a), the synchronization waveform illustrated in FIG. 10(a) can be obtained by associating “0” with Low of the synchronization waveform and associating “1” with High of the synchronization waveform.

As described above, tolerance to pulses not being captured is increased by using the M-sequence code as a synchronization waveform transmitted by the touch panel controller 10 and by determining whether pulses match the same M-sequence code in the sense circuit 35 and the synchronization signal detector circuit 36 of the stylus pen 3. However, when the sequence is long, the sequence includes a pattern in which the number of continuous Highs or Lows is large. Thus, when the reset timing that sets a reference potential is set in this part, an unnecessary potential change occurs to make the determination of a waveform difficult.

For example, an internal waveform when there are High pulses in a long period in the synchronization waveform transmitted by the touch panel controller 10 as illustrated in FIG. 11(a) and when a reference potential is set at the reset timing R3 in the input waveform received by the stylus pen 3 illustrated in FIG. 11(b) becomes as illustrated in FIG. 11(c), and it is difficult to detect the internal waveform.

Therefore, the present embodiment uses a waveform that is obtained by Manchester-coding a code having good autocorrelation characteristics such as the M-sequence, and the waveform is driven as the synchronization waveform of the touch panel controller 10. The Manchester-coded waveform means associating “0” with High→Low of the synchronization waveform and associating “1” with Low→High of the synchronization waveform as illustrated in FIG. 10(b). The opposite may also be possible. Accordingly, as illustrated in FIG. 10(b), it is possible to prevent the occurrence of a case where the period of High or Low is long when the M-sequence code “1110010” is used.

As such, considering the reset operation, it is preferable that the Manchester-coded M-sequence code or Gold sequence code is used.

In the present embodiment, as illustrated in FIG. 12(a), for example, the above 7-bit M-sequence code “1110010” that is Manchester-coded is used to associate pulses as illustrated in FIG. 12(a). Then, the pulses are used as a synchronization waveform of the touch panel controller 10 as illustrated in FIG. 12(b).

Accordingly, a period of long continuous Highs or Lows does not appear in the synchronization waveform, and it is possible to use a synchronization pattern of which the autocorrelation characteristics facilitate the detection of the synchronization pattern. In addition, since High or Low is continuous at most during a time that represents one bit in the synchronization waveform, it is also possible to adjust the reset timing that sets a reference potential by the reception-side stylus pen 3.

For example, when a state where potential is high continues for the time that represents one bit or longer, this is regarded as the influence of noise, and the potential at that point in time is set for a later reference potential. In addition, when the state changes from the high potential close to the reference potential, the potential at that point in time is set for a later reference potential. Accordingly, even when potential significantly decreases due to noise and the like, it is possible to track the potential.

(Continuous Operation of Synchronization of Touch Panel System and Stylus Pen and Touch Position Detection)

Continuous operation of the synchronization of the touch panel system 1 and the stylus pen 3 having the above configurations and touch position detection will be described on the basis of FIG. 13 and FIGS. 14(a) to 14(c). FIG. 13 is an operation image diagram illustrating a correspondence between a drive operation of the touch panel controller 10 and a drive operation of the stylus pen 3. FIGS. 14(a) to 14(c) are diagrams illustrating a specific drive operation in a synchronization signal detection period, a pause period, and a normal drive period illustrated in FIG. 13.

The drive operation of the stylus pen 3, as illustrated in FIG. 13, is configured by repeating three periods of a synchronization signal detection period that is set for detecting the synchronization signal from the touch panel controller 10 with the sense circuit 35 and the synchronization signal detector circuit 36 by turning the operation changing switch 34 a ON and by turning the operation changing switch 34 b OFF, a preparation period, and a drive mode period during which the drive circuit 38 drives the pen tip portion 31 by turning the operation changing switch 34 a OFF and by turning the operation changing switch 34 b ON.

The synchronization signal detection period is a standby period for detecting a bit pattern that represents the synchronization waveform and is a period during which the synchronization signal pattern is detected from a pen tip signal waveform while the pen tip portion 31 is not driven. Specifically, in the synchronization signal detection period, as illustrated in FIG. 14(a), each of the drive lines DL₁ to DL_(L) of the driver 12 is driven with the same waveform. The pattern of the waveform used includes a pattern that has autocorrelation characteristics such as the M-sequence.

The preparation period illustrated in FIG. 13 is a preparation period for selecting a code to drive on the basis of additional information after the detection of the synchronization signal pattern and on the basis of the state of the stylus pen 3 and for starting to drive the pen tip in accordance with the timing of the touch panel controller 10 and is a period during which the additional information that includes the timing of starting driving is interpreted.

The drive mode period is a period during which the pen tip portion 31 is driven by the drive circuit 38 and is a period during which the pen tip portion 31 is driven with the selected code while the edge of the drive waveform is finely adjusted in accordance with the drive timing of the touch panel controller 10. At this time, the drive circuit 38 of the stylus pen 3 is driven in accordance with the drive timing of the touch panel controller 10.

Meanwhile, the drive operation of the touch panel controller 10 is configured by repeating three periods of a period during which the drive lines DL₁ to DL_(L) are driven with the same waveform, a pause period, and a period during which driving of the drive lines DL₁ to DL_(K) and driving of the sense lines SL1 to SL_(K) to SL_(L) are switched.

The period during which the drive lines DL₁ to DL_(L) are driven with the same waveform is a period during which the additional information + the synchronization waveform for the synchronization of the stylus pen 3 are driven. Specifically, as illustrated in FIG. 14(b), the drive lines DL₁ to DL_(L) are driven with the same waveform.

The pause period is a period during which the stylus pen 3 ends the detection of synchronization and prepares for driving. Specifically, as illustrated in FIG. 14(b), the pause period is a standby period for disposing a preparation period during which the stylus pen 3 detects the synchronization waveform and performs normal driving. Thus, the drive waveform during the pause period does not have any meaning and is completely arbitrary. Therefore, driving may not be performed in the pause period. This duration is not necessary when the preparation period on the stylus pen 3 side is not necessary.

Next, the period during which driving of the drive lines DL₁ to DL_(K) to DL_(L) and driving of the sense lines SL1 to SL_(K) to SL_(L) are switched is a normal drive period for position detection that is performed to obtain data of one face of the touch panel 2. Specifically, in the normal drive period, as illustrated in FIG. 14(c), driving of the drive lines DL₁ to DL_(K) to DL_(L) with a waveform necessary for detecting the position of a touch of the stylus pen 3 and sensing are repeated. Methods for driving include sequential driving and parallel driving. In FIG. 14(c), sequential driving is represented so as to facilitate visual understanding of the order of drive patterns.

The stylus pen 3, when detecting the synchronization waveform, drives the pen tip portion 31 with the same waveform as the drive lines DL_(L+1) and DL_(L+2) that correspond to the outside of the touch panel 2. In FIG. 14(c), colored backgrounds indicate a sense period, that is, a period during which a charge signal of an electrostatic capacitance for detecting the position of a touch is detected.

(Output Operation of Stylus Pen Outputting Quantitative Characteristic Value Such as Pen Pressure Level)

A mechanism of outputting a quantitative characteristic value such as a pen pressure level in the stylus pen 3 of the present embodiment will be described on the basis of FIG. 1, FIG. 15, and FIG. 16. FIG. 15 is a diagram illustrating a relationship between a drive pattern of the driver in the touch panel controller and a drive pattern of the drive circuit in the stylus pen. FIG. 16 is a diagram illustrating a pen pressure value that is obtained in the stylus pen and a pen pressure value that is represented in the stylus pen having the pen pressure and in the touch panel controller.

As described above, the stylus pen 3 of the present embodiment is provided with the pen pressure sensor 31 d and is configured of an electronic pen that outputs a quantitative characteristic value such as a pen pressure level. Thus, in order to transmit a quantitative characteristic value that is detected by the stylus pen 3 to the touch panel controller 10 side, the transmission has to use many types of identifiable signals because there are many types of information. As a consequence, a problem arises in that the amount of signals increases, requiring more time for transmission, and the identification of the signal on the reception side becomes complicated.

In the present embodiment, therefore, as illustrated in FIG. 1 and FIG. 15, the stylus pen 3 is configured of an electronic pen that outputs a quantitative characteristic value, and the stylus pen 3 produces an output that indicates that the quantitative characteristic value in the stylus pen 3 is increased from the characteristic value of the previous output by using a waveform that corresponds to the drive line DL_(L+1) as the (L+1)-th drive signal line. Meanwhile, the stylus pen 3 produces an output that indicates that the quantitative characteristic value in the stylus pen 3 is decreased from the characteristic value which is updated and retained in the previous output by using a waveform that corresponds to the drive line DL_(L+2) as the (L+2)-th drive signal line. Furthermore, in order to determine a next increase or decrease, the result of the current output of an increase or decrease is reflected on the characteristic value that is retained internally. The touch panel controller 10 is provided with a conversion output unit 19 that converts and outputs a quantitative characteristic value by using the sum of the initial value of the quantitative characteristic value and the number of outputs × the unit amount of increase or decrease in the waveform that corresponds to the (L+1)-th drive line DL_(L+1) or in the waveform that corresponds to the (L+2)-th drive line DL_(L+2).

Specifically, as illustrated in FIG. 15, when the stylus pen 3 detects pen pressure with the pen pressure sensor 31 d and when the pen pressure value of the pen pressure sensor 31 d is increased from the value of the previous output, the stylus pen 3 drives the pen tip portion 31 with the waveform that corresponds to the drive line DL_(L+1) while the driver 12 of the touch panel controller 10 drives the drive lines DL₁ to DL_(L). Alternatively, when the stylus pen 3 detects pen pressure with the pen pressure sensor 31 d and when the pen pressure value of the pen pressure sensor 31 d is decreased from the value of the previous output, the stylus pen 3 drives the pen tip portion 31 with the waveform that corresponds to the drive line DL_(L+2) while the driver 12 of the touch panel controller 10 drives the drive lines DL₁ to DL_(L).

Accordingly, by the waveforms that correspond to the drive lines DL_(L+1) and DL_(L+2), an increasing or decreasing signal of the pen pressure sensor 31 d in the stylus pen 3 is output, and the signal is detected by the sense lines SL₁ to SL_(L) through the horizontal signal lines HL₁ to HL_(K) or through the vertical signal lines VL₁ to VL_(L) that pass through the position of a touch on the touch panel 2 at that time.

When the pen pressure value is not transmitted from the stylus pen 3 yet, the value of the previous output, that is, the characteristic value that is retained internally is set to “0”. For example, at the start of a touch, the previously transmitted value, that is, the characteristic value that is retained internally is “0”.

An interval during which a pen pressure increase or decrease signal of the pen pressure sensor 31 d is transmitted from the stylus pen 3 occurs once in a drive period during which the driver 12 drives the drive lines DL₁ to DL_(L) once. While driving performed by sequential driving is illustrated in FIG. 15 for easy understanding, driving may be performed by parallel driving.

That is, in the present embodiment, the stylus pen 3 transmits only two types of information that indicates whether the quantitative characteristic value is increased or decreased from the characteristic value of the previous output. However, by using the two types of information, it is possible to obtain whether the pen pressure value of the pen pressure sensor 31 d is increased or decreased on the touch panel controller 10 side.

As illustrated in FIG. 1, the conversion output unit 19 is disposed in the touch panel controller 10. A summation unit 19 a of the conversion output unit 19 is configured to convert and output the quantitative characteristic value by using the sum of the initial value of the quantitative characteristic value and the number of outputs × the unit amount of increase or decrease in the waveform that corresponds to the (L+1)-th drive line DL_(L+1) or in the waveform that corresponds to the (L+2)-th drive line DL_(L+2). A positive value is used for the unit amount of increase or decrease when counting the output of the waveform that corresponds to the (L+1)-th drive line DL_(L+1). Meanwhile, a negative value is used for the unit amount of increase or decrease when counting the output of the waveform that corresponds to the (L+2)-th drive line DL_(L+2).

Accordingly, even when a quantitative characteristic value that has many types of information is output, only two types of signals related to increase and decrease are used. Thus, the amount of signals is small, and transmission can be performed in a short amount of time. For example, when the characteristic value is obtained in 10 bits, more time is required because transmission is performed in any form ten times more than one-bit information of increase or decrease. Signal processing in the conversion output unit 19 of the reception-side touch panel controller 10 is simplified because it is only necessary to obtain the cumulative value of increase and decrease from the initial value of the quantitative characteristic value.

As a consequence, for example, the pen pressure value illustrated in FIG. 16 can be obtained. The pen pressure value data illustrated in FIG. 16 starts with an initial value of “0”. It is assumed that the pen pressure value has a value in the range of 0 to 1.0 and that the actual pen pressure value obtained in the pen tip portion 31 of the stylus pen 3 is illustrated by a curve in FIG. 16.

As an internal process of the stylus pen 3 performed on the curve, the pen pressure is represented by a value that changes by 0.2. This internal process is performed by the controller circuit 33 of the stylus pen 3. In the controller circuit 33, a determination of whether the internal pen pressure value has to be increased or decreased to approach the pen pressure value of the curve is performed, and the internal pen pressure value is updated on the basis of the determination. The increase or decrease is represented as a drive waveform of the pen tip portion 31.

On the touch panel controller 10 side that receives the increase or decrease information, a pen pressure value change that is the same as the internal pen pressure value of the stylus pen 3 can be reproduced by the sum of the initial value “0” as a reference and the number of outputs × the unit amount of increase or decrease “0.2” obtained by the conversion output unit 19.

Therefore, when the stylus pen 3 that outputs a quantitative characteristic value such as pen pressure data which has many types of information is used, it is possible to provide the touch panel system 1 that may transmit the information simply in a short amount of time.

As such, in the touch panel system 1 of the present embodiment, since the driver 12 as a synchronization signal transmission unit of the touch panel controller 10 transmits the synchronization signal to the stylus pen 3 during synchronization signal transmission periods immediately before each of the first signal line drive period and the second signal line drive period, it is possible to create the synchronization signal by using a drive signal for driving the first signal lines and the second signal lines. Thus, a separate circuit for creating the synchronization signal is not disposed, and the number of components can be reduced. Regarding a typical touch detection drive pattern, the M-sequence may be used in parallel driving. When the M-sequence is also used for the synchronization signal, it is not necessary to dispose a separate circuit. However, a separate circuit is required in sequential driving because it is necessary to generate the synchronization signal. A separate circuit is also required even in parallel driving when driving is performed by using a Hadamard matrix that has orthogonality since the Hadamard matrix is different from the M-sequence of the synchronization signal.

When the synchronization signal is wirelessly transmitted from the touch panel controller 10 to the stylus pen 3, low-frequency signals are superimposed as noise on the synchronization signal. Thus, the synchronization signal may not be captured when noise is not appropriately separated in the case of a single pulse. Meanwhile, in the case of a plurality of unchanging pulses that has the same pitch, it is unclear which part corresponds to the synchronization signal.

Therefore, in the present embodiment, the driver 12 of the touch panel controller 10 transmits a synchronization signal having a waveform that is configured of a pseudorandom sequence having periodicity such as the M-sequence code or the Gold sequence code to the stylus pen 3 during the synchronization signal transmission period, and the stylus pen 3 is provided with the sense circuit 35 and the synchronization signal detector circuit 36 as a synchronization signal detecting unit that detects the synchronization signal.

Thus, the synchronization signal, since being transmitted with a waveform that is configured of a pseudorandom sequence having periodicity, has good autocorrelation characteristics. Thus, accuracy increases in identifying the synchronization signal, and it is possible to reduce the synchronization signal not being captured.

Therefore, it is possible to provide the touch panel system 1 that can appropriately detect the synchronization signal.

When the synchronization signal on which low-frequency components are superimposed is received and when the reset operation is performed with pulses having a long High period or Low period in the case of detecting the amplitude of the synchronization signal by periodically performing the reset operation to return the received input waveform to the reference potential, potential changes unnecessarily, and it is difficult to determine the waveform.

Therefore, in the present embodiment, the synchronization signal having a waveform configured of a pseudorandom sequence is Manchester-coded. That is, in the Manchester-coding process, a process of associating “0” of the pseudorandom sequence with High→Low of the synchronization waveform and associating “1” with Low→High of the synchronization waveform is performed. The opposite may also be possible. Accordingly, it is possible to prevent the period of High or Low from being lengthened.

In the touch panel system 1 of the present embodiment, the driver 12 as a synchronization signal transmission unit of the touch panel controller 10 doubles as the driver 12 as a drive unit that supplies a drive signal for driving the horizontal signal lines HL₁ to HL_(K) as the plurality of first signal lines or the vertical signal lines VL₁ to VL_(L) as the plurality of second signal lines. The driver 12 transmits the synchronization signal by changing the drive signal for driving the plurality of horizontal signal lines HL₁ to HL_(K) or the plurality of vertical signal lines VL₁ to VL_(L) to a waveform that is configured of a Manchester-coded pseudorandom sequence having periodicity.

Accordingly, since the synchronization signal transmission unit is configured of the driver 12 that doubles as a drive unit, it is possible to create the synchronization signal by simply changing the waveform pattern of the drive signals of the drive lines DL₁ to DL_(L) that are used to drive the horizontal signal lines HL₁ to HL_(K) and the vertical signal lines VL₁ to VL_(L). Thus, a separate circuit for creating the synchronization signal is not disposed, and the number of components can be certainly reduced. As described above, this result is limited to the case where the M-sequence is also used for the synchronization signal in parallel driving.

The touch panel system 1 of the present embodiment is provided with the stylus pen 3 as a touch pen, the touch panel 2, and the touch panel controller 10. The touch panel 2 has electrostatic capacitances formed at each intersection of the horizontal signal lines HL₁ to HL_(K) as the K (K is an integer greater than or equal to two) numbers of the first signal lines and the vertical signal lines VL₁ to VL_(L) as the L (L is an integer satisfying L≧K) numbers of the second signal lines. The touch panel controller 10 outputs drive signals that drive the K numbers of the horizontal signal lines HL₁ to HL_(K) or the L numbers of the vertical signal lines VL₁ to VL_(L) from the driver 12 as a drive unit through the drive lines DL₁ to DL_(L) as the L numbers of drive signal lines and receives input of detection signals from the K numbers of the horizontal signal lines HL₁ to HL_(K) or the L numbers of the vertical signal lines VL₁ to VL_(L) detected by the sense amplifier 13 as a detecting unit through the sense lines SL₁ to SL_(L) as the L numbers of detection signal lines on the basis of a change in charges accumulated in the electrostatic capacitances due to the stylus pen 3 when the stylus pen 3 touches the touch panel 2.

The stylus pen 3 is configured of an electronic pen that outputs a quantitative characteristic value, and the stylus pen 3 produces an output that indicates that the quantitative characteristic value in the stylus pen 3 is increased from the characteristic value of the previous output by using the waveform that corresponds to the (L+1)-th drive line DL_(L+1) and, meanwhile, produces an output that indicates that the quantitative characteristic value in the stylus pen 3 is decreased from the characteristic value of the previous output by using a waveform that corresponds to the (L+2)-th drive line DL_(L+2). The touch panel controller 10 is provided with the conversion output unit 19 that converts and outputs a quantitative characteristic value by using the sum of the initial value of the quantitative characteristic value and the number of outputs × the unit amount of increase or decrease in the waveform that corresponds to the (L+1)-th drive line DL_(L+1) or in the waveform that corresponds to the (L+2)-th drive line DL_(L+2).

Accordingly, since only two types of signals related to increase and decrease are used even when a quantitative characteristic value that has many types of information is output, the amount of signals is small, and transmission can be performed in a short amount of time. In addition, signal processing on the reception side is simplified because it is only necessary to obtain the cumulative value of increase and decrease from the initial value of the quantitative characteristic value.

Therefore, when the stylus pen 3 that outputs a quantitative characteristic value which has many types of information is used, it is possible to provide the touch panel system 1 that may transmit the information simply in a short amount of time.

In the touch panel system 1 of the present embodiment, the stylus pen 3 as an electronic pen is provided with the pen pressure sensor 31 d. Accordingly, it is possible to detect a pen pressure level that is a quantitative characteristic value when the stylus pen 3 touches the touch panel 2.

The present invention is not limited to the above embodiment. Various modifications can be carried out within the scope of the present invention. For example, while the pen pressure level of the pen pressure sensor 31 d is used as an example of a quantitative characteristic value in the embodiment, the present invention is not particularly limited to this.

As an example of a quantitative characteristic value, for example, a shade level can also be used as a quantitative characteristic value when, for example, a colored character is displayed by the stylus pen 3.

Second Embodiment

Another embodiment of the present invention will be described as follows on the basis of FIG. 17 to FIG. 20. Configurations other than those described in the present embodiment are the same as those of the first embodiment. For convenience of description, members having the same function as the members illustrated in the drawings of the first embodiment will be designated by the same reference sign, and descriptions thereof will be omitted.

The touch panel system 1 of the present embodiment is different in that the conversion output unit 19 of the touch panel controller 10 can change the unit amount of increase or decrease.

A configuration of the touch panel system 1 of the present embodiment will be described on the basis of FIG. 17. FIG. 17 is a block diagram illustrating the configuration of the touch panel system 1 of the present embodiment.

In the touch panel system 1 of the present embodiment, as illustrated in FIG. 17, a unit increase or decrease amount changing unit 19 b that changes the unit amount of increase or decrease is disposed in the conversion output unit 19.

When, for example, the quantitative characteristic value of the stylus pen 3 is generated in a short amount of time, a difference occurs between the quantitative characteristic value and the actual quantitative characteristic value of the stylus pen 3 if the unit amount of increase or decrease is not increased.

In the present embodiment, therefore, the unit increase or decrease amount changing unit 19 b is disposed in the conversion output unit 19, and the unit amount of increase or decrease is changed by the unit increase or decrease amount changing unit 19 b. Accordingly, it is possible to suppress the occurrence of a difference between the quantitative characteristic value and the actual quantitative characteristic value of the stylus pen 3.

What can be detected by the conversion output unit 19 is only the number of outputs in a certain amount of time in the waveform that corresponds to the (L+1)-th drive line DL_(L+1) or in the waveform that corresponds to the (L+2)-th drive line DL_(L+2). Therefore, the problem is how the unit increase or decrease amount changing unit 19 b determines whether to change the unit amount of increase or decrease.

In the present embodiment, therefore, as illustrated in FIG. 17, a continuous increase or decrease changing unit 19 c is disposed in the unit increase or decrease amount changing unit 19 b. The continuous increase or decrease changing unit 19 c is configured to increase or decrease the unit amount of increase or decrease from the previous value when the number of continuous outputs in each of the waveform that corresponds to the (L+1)-th drive line DL_(L+1) and the waveform that corresponds to the (L+2)-th drive line DL_(L+2) is P (P is an integer greater than or equal to two).

That is, for example, when the number of continuous outputs in the waveform that corresponds to the (L+1)-th drive line DL_(L+1) is P (P is an integer greater than or equal to two), it is determined that a rapid change occurs, and the unit amount of increase or decrease is, for example, doubled. When increase further continues, the unit amount of increase or decrease is further increased.

Specifically, for example, as illustrated in FIG. 18, when the internal pen pressure value of the stylus pen 3 is represented by changing the unit amount of increase or decrease by 0.1, there may be a case where the internal pen pressure value cannot sufficiently keep up with the speed of change even in the case of the same amount of a pen pressure change.

In the present embodiment, therefore, as illustrated in FIG. 19, the unit amount of increase or decrease is increased from 0.1 to 0.2 when the pen pressure value is continuously increased or decreased twice. When the pen pressure value is further increased or decreased once more, the unit amount of increase or decrease is further increased to 0.3.

Meanwhile, when increase or decrease does not continue, the unit amount of increase or decrease is decreased. When increase and decrease are continuously repeated, the unit amount of increase or decrease is further decreased. As such, for example, the next unit amount of increase or decrease is increased when increase or decrease continues twice, or otherwise, the next unit amount of increase or decrease is decreased.

The unit amount of increase or decrease is increased or decreased by 0.1. However, the range of increase or decrease of the unit amount of increase or decrease is greater than or equal to 0.1 and less than or equal to 0.3.

While the pen pressure value is reproduced by disposing the unit increase or decrease amount changing unit 19 b in the touch panel controller 10 in the present embodiment, it is also possible that the pen pressure is transmitted to the touch panel controller 10 side by disposing the unit increase or decrease amount changing unit 19 b and the continuous increase or decrease changing unit 19 c on the stylus pen 3 side. Accordingly, in the conversion output unit 19 of the touch panel controller 10, if an increase or decrease in the pen pressure value is obtained, the unit amount of increase or decrease can be set to the same state as the range of change in the stylus pen 3 by finding how many times an increase or decrease in the pen pressure value continues, and the same pen pressure as the internal pen pressure value of the stylus pen 3 can be reproduced by using the range of change and the increase or decrease information.

In the case of outputting the internal pen pressure value of the stylus pen 3, for example, as illustrated in FIG. 18, when the internal pen pressure value of the stylus pen 3 is represented by changing the unit amount of increase or decrease by 0.1, it is possible to perform the following process when the internal pen pressure value cannot sufficiently keep up with the speed of change even in the case of the same amount of a pen pressure change.

That is, as illustrated in FIG. 20, the interval between determinations is reduced in half while the range of increase or decrease of the unit amount of increase or decrease is maintained to 0.1. Accordingly, since the speed of change of pen pressure relatively decreases when the interval between determinations is short, the representation of the internal pen pressure value is not delayed.

Third Embodiment

Another embodiment of the present invention will be described as follows on the basis of FIG. 21 to FIG. 26. Configurations other than those described in the present embodiment are the same as those of the first embodiment. For convenience of description, members having the same function as the members illustrated in the drawings of the first embodiment will be designated by the same reference sign, and descriptions thereof will be omitted.

(Synchronization Operation of Touch Panel Controller and Stylus Pen of Present Embodiment)

In the present embodiment, synchronization of the stylus pen 3 and, furthermore, a method that may prevent the pulses of the dedicated synchronization signal from not being captured will be described on the basis of FIG. 21(a) to FIG. 25(c). FIG. 21(a) is a waveform diagram illustrating an input waveform of a synchronization signal received by the stylus pen in the touch panel system of the present embodiment, and FIG. 21(b) is a waveform diagram illustrating an internal waveform when a reference potential is set at reset timings R1 to R6. FIG. 22(a) is a waveform diagram illustrating an example of a synchronization waveform transmitted from the touch panel controller, FIG. 22(b) is a waveform diagram illustrating reset timings R7, R7, and R8 of an input waveform received by the stylus pen, and FIG. 22(c) is a waveform diagram illustrating a synchronization waveform when a reference potential is set at the reset timings R7, R7, and R8 illustrated in FIG. 22(b). FIG. 23 is a timing chart illustrating output waveforms of the touch panel controller in which a fixing period is disposed immediately before a synchronization waveform is output. FIG. 24(a) is a waveform diagram illustrating an example of a synchronization waveform transmitted from the touch panel controller, FIG. 24(b) is a waveform diagram illustrating reset timings R11, R12, and R13 of an input waveform received by the stylus pen, and FIG. 24(c) is a waveform diagram illustrating a synchronization waveform when a reference potential is set at the reset timings R11, R12, and R13 illustrated in FIG. 24(b). FIG. 25(a) is a diagram illustrating a method for transmitting a synchronization waveform that is transmitted by drive lines DL₁ to DL_(L) of the driver in the touch panel controller, FIG. 25(b) is a waveform diagram illustrating an input waveform received by the stylus pen, and FIG. 25(c) is a waveform diagram illustrating a synchronization waveform when a reference potential is set after the input waveform is initially reset in the fixing period illustrated in FIG. 25(b).

When the reset operation is performed at the reset timings R1 to R6 where a reference potential is set in a case where the input waveform illustrated in FIG. 21(a) is obtained in the stylus pen 3, the internal waveform illustrated in FIG. 21(b) is obtained.

In this case, even when the Manchester-coded M-sequence code is used, as illustrated in FIGS. 22(a) to 22(c), the same signal has different potentials depending on the timing of the reset operation that sets a reference potential, and the difficulty of identifying whether the synchronization waveform output of the touch panel controller 10 is High or Low remains the same. That is, it is difficult to find whether a second peak is High or Low.

Therefore, in the present embodiment, as illustrated in FIG. 23, a fixing period F is disposed immediately before the output of the synchronization waveform to fix the output waveform of the touch panel controller 10. The time of fixing is set to a time in which the timing of the reset operation that sets a reference potential in the reception-side stylus pen 3 is included at least once.

Accordingly, a stable potential can be set as a reference potential before the synchronization waveform is output.

Specifically, as illustrated in FIGS. 24(a) and 24(b), the reset timings R11, R12, and R13 are disposed in the fixing period F to set a reference potential. Accordingly, as illustrated in FIG. 18(c), the identification of whether the output of the touch panel controller 10 is High or Low is facilitated when the synchronization waveform is detected.

As a consequence, as illustrated in FIG. 23, the potential when the reset operation ends becomes a reference potential by disposing the fixing period F before the synchronization waveform is output. Thus, as illustrated in FIGS. 25(a) to 25(c), by disposing the fixing period F that is longer than the interval between the reset operations in the stylus pen 3, the reset operation is certainly performed once or more prior to the synchronization signal detection period in a state where the drive potential of the touch panel controller 10 is set, and the waveform can be shaped in a stable state from the start of the synchronization signal detection period.

(Continuous Operation of Synchronization of Touch Panel System and Stylus Pen and Touch Position Detection)

Continuous operation of the synchronization of the touch panel system 1 and the stylus pen 3 having the above configurations and touch position detection will be described on the basis of FIG. 26 and FIG. 27. FIG. 26 is an operation image diagram illustrating a correspondence between a drive operation of the touch panel controller 10 and a drive operation of the stylus pen 3. FIG. 27 is a diagram illustrating a specific drive operation in the fixing period illustrated in FIG. 26. In the description of FIG. 26 and FIG. 27, the same part as FIG. 13 and FIGS. 14(a) to 14(c) of the first embodiment will be briefly described.

The stylus pen 3, as illustrated in FIG. 26, includes the synchronization signal detection period for detecting the synchronization signal from the touch panel controller 10 with the sense circuit 35 and the synchronization signal detector circuit 36, the preparation period, and the drive mode period during which the pen tip portion 31 is driven by the drive circuit 38.

The synchronization signal detection period, the preparation period, and the drive mode period are the same as those described in FIG. 13 and FIGS. 14(a) to 14(c).

Meanwhile, the touch panel controller 10 includes the fixing period F, the period during which the drive lines DL₁ to DL_(L) are driven with the same waveform, the pause period, and a period during which the drive lines DL₁ to DL_(L) are driven and during which a change in charges of the electrostatic capacitances is read by the sense lines SL₁ to SL_(L).

The fixing period F is a period for stabilizing a signal level with which the stylus pen 3 detects synchronization. Specifically, in the fixing period F, as illustrated in FIG. 21, the drive lines DL₁ to DL_(L) are fixed to either Low or High. Although any of Low and High is favorable, the drive lines DL₁ to DL_(L) are fixed to Low in the present embodiment. Thus, the drive lines DL₁ to DL_(L) of the touch panel controller 10 have zero potentials. At this time, the drive line DL_(L+1) for the pen pressure sensor 31 d of the stylus pen 3 is not driven.

The period during which the drive lines DL₁ to DL_(L) are driven with the same waveform is a period during which the additional information + the synchronization waveform for the synchronization of the stylus pen 3 are driven. Specifically, as illustrated in FIG. 14(b), the drive lines DL₁ to DL_(L) are driven with the same waveform.

The pause period is a period during which the stylus pen 3 ends the detection of synchronization and prepares for driving. Specifically, as illustrated in FIG. 14(b), the pause period is a standby period for disposing a preparation period during which the stylus pen 3 detects the synchronization waveform and performs normal driving. Thus, the drive waveform during the pause period does not have any meaning and is completely arbitrary. Therefore, driving may not be performed in the pause period. In addition, the stylus pen 3 does not drive the pen tip portion 31 with the waveforms that correspond to the drive lines DL_(L+1) and DL_(L+2). This duration is not necessary when the preparation period on the stylus pen 3 side is not necessary.

Next, the period during which the drive lines DL₁ to DL_(L) are driven and during which a change in charges of the electrostatic capacitances is read by the sense lines SL₁ to SL_(L) is a normal drive period for position detection that is performed to obtain data of one face of the touch panel 2. Specifically, in the normal drive period, as illustrated in FIG. 14(c), driving of the drive lines DL₁ to DL_(L) and reading from the sense lines SL₁ to SL_(L) are repeated. Methods for driving include sequential driving and parallel driving. In FIG. 14(c), sequential driving is represented so as to facilitate visual understanding of the order of drive patterns.

The stylus pen 3, when detecting the synchronization waveform, drives the pen tip portion 31 with the waveforms that correspond to the drive lines DL_(L+1) and DL_(L+2) which correspond to the outside of the touch panel 2. That is, the stylus pen 3 outputs waveforms that correspond to the drive lines DL_(L+1) and DL_(L+2) in accordance with driving of the drive lines DL₁ to DL_(L) by the touch panel controller 10. In FIG. 14(c), colored backgrounds indicate a sense period, that is, a period during which a charge signal of an electrostatic capacitance is detected.

As such, in the touch panel system 1 of the present embodiment, the sense circuit 35 and the synchronization signal detector circuit 36 as a synchronization signal detecting unit of the stylus pen 3 as an electronic pen detect the amplitude of the synchronization signal by periodically performing the reset operation to return the received input waveform to the reference potential when the synchronization signal on which low-frequency components are superimposed is received. Accordingly, it is possible to detect the amplitude of the synchronization signal inexpensively without using an expensive low frequency cut-off filter for the removal of low-frequency components superimposed as noise.

When the reset operation overlaps with a High part of a pulse while the reset operation is arbitrarily performed on the received input waveform, the subsequent signal waveform becomes negative, and thus the positive High part of the pulse cannot be recognized correctly. As a consequence, the synchronization signal may not be captured.

Therefore, in the present embodiment, the synchronization signal transmission period is configured of the fixing period F during which a fixed synchronization signal of which the waveform is fixed to High or Low is transmitted and a pseudorandom sequence waveform period during which the synchronization signal of which the waveform is configured of a pseudorandom sequence having periodicity such as the M-sequence code or the Gold sequence code is transmitted. In the fixing period F, the reset operation is performed at least once.

Accordingly, since the input waveform returns to the reference potential in the fixing period F during which the waveform is fixed to High or Low, it is possible to appropriately determine whether the subsequent pulse is High or Low.

Fourth Embodiment

Still another embodiment of the present invention will be described as follows on the basis of FIG. 28. Configurations other than those described in the present embodiment are the same as those of the first embodiment and the second embodiment. For convenience of description, members having the same function as the members illustrated in the drawings of the first embodiment and the second embodiment will be designated by the same reference sign, and descriptions thereof will be omitted.

In the present embodiment, a case where the touch panel system 1 is mounted on a mobile phone as an electronic device will be described on the basis of FIG. 28. FIG. 28 is a block diagram illustrating a configuration of the mobile phone.

A mobile phone 60 of the present embodiment, as illustrated in FIG. 28, is provided with the touch panel system 1, a display panel 61, an operating key 62, a loudspeaker 63, a microphone 64, a camera 65, a CPU 66, a ROM 67, a RAM 68, and a display controller circuit 69. The constituent elements are connected to each other by a data bus.

The touch panel system 1, as described above, includes the touch panel 2, the touch panel controller 10 that detects an electrostatic capacitance or an electrostatic capacitance difference, and the stylus pen 3.

The display panel 61 uses the display controller circuit 69 to display an image stored on the ROM 67 and the RAM 68. In addition, the display panel 61 either overlies the touch panel 2 or incorporates the touch panel 2. It is also possible to cause a touch recognition signal that indicates the position of a touch on the touch panel 2 and that is generated by the touch recognizing unit 17 to play the same role as a signal that indicates that the operating key 62 is operated.

The operating key 62 receives an instruction that is input by a user of the mobile phone 60.

The loudspeaker 63 outputs sound that is based on, for example, music data stored on the RAM 68.

The microphone 64 receives input of the voice of the user. The mobile phone 60 digitizes the input voice (analog data). Then, the mobile phone 60 transmits the digitized voice to a communication opponent (for example, other mobile phones).

The camera 65 captures an image of a subject in response to the user operating the operating key 62. The captured image data of the subject is stored on the RAM 68 or an external memory (for example, a memory card).

The CPU 66 controls the operation of the touch panel system 1 and the mobile phone 60. The CPU 66, for example, executes programs stored on the ROM 67.

The ROM 67 stores data in a non-volatile manner. In addition, the ROM 67 is a ROM such as an erasable programmable read-only memory (EPROM) or a flash memory on which data can be written and deleted. Although illustration is not provided in FIG. 28, the mobile phone 60 may be configured to be provided with an interface (IF) for wired connection to other electronic devices.

The RAM 68 stores data that is generated by the CPU 66 executing a program or data that is input through the operating key 62 in a volatile manner.

As such, the mobile phone 60 as an electronic device in the present embodiment is provided with the touch panel system 1. Accordingly, it is possible to provide the mobile phone 60 as an electronic device that is provided with the touch panel system 1 which can appropriately detect the synchronization signal.

CONCLUSION

In order to resolve the above problem, the touch panel system 1 in a first aspect of the present invention includes a touch pen (stylus pen 3), the touch panel 2 that has electrostatic capacitances formed at each intersection of the K (K is an integer greater than or equal to two) numbers of the first signal lines (horizontal signal lines HL₁ to HL_(K)) and the L (L is an integer satisfying L≧K) numbers of the second signal lines (vertical signal lines VL₁ to VL_(L)), and the touch panel controller 10. In the touch panel system 1, the touch panel controller 10 outputs drive signals that drive the K numbers of the first signal lines (horizontal signal lines HL₁ to HL_(K)) or the L numbers of the second signal lines (vertical signal lines VL₁ to VL_(L)) from a drive unit (driver 12) through L numbers of drive signal lines (drive lines DL₁ to DL_(L)) and receives input of detection signals from the K numbers of the first signal lines (horizontal signal lines HL₁ to HL_(K)) or the L numbers of the second signal lines (vertical signal lines VL₁ to VL_(L)) detected by a detecting unit (sense amplifier 13) through L numbers of detection signal lines (sense lines SL₁ to SL_(L)) on the basis of a change in charges accumulated in the electrostatic capacitances due to the touch pen (stylus pen 3) when the touch pen (stylus pen 3) touches the touch panel 2. The touch pen (stylus pen 3) is configured of an electronic pen that outputs a quantitative characteristic value. The electronic pen (stylus pen 3) produces output that indicates that the quantitative characteristic value of the electronic pen (stylus pen 3) is increased from the characteristic value of the previous output by using the waveform that corresponds to an (L+1)-th drive signal line (drive line DL_(L+1)) other than the L numbers of the drive signal lines (drive lines DL₁ to DL_(L)) and, meanwhile, produces output that indicates that the quantitative characteristic value of the electronic pen (stylus pen 3) is decreased from the characteristic value of the previous output by using the waveform that corresponds to an (L+2)-th drive signal line (drive line DL_(L+2)) other than the L numbers of the drive signal lines (drive lines DL₁ to DL_(L)). The touch panel controller 10 includes the conversion output unit 19 that converts and outputs the quantitative characteristic value by using the sum of the initial value of the quantitative characteristic value and the number of outputs × the unit amount of increase or decrease in the waveform which corresponds to the (L+1)-th drive signal line (drive line DL_(L+1)) or in the waveform which corresponds to the (L+2) -th drive signal line (drive line DL_(L+2)). The representation of L+1 and L+2 is for representing drive signal lines other than the L numbers or the K numbers of drive signal lines, meaning that the drive signals are not actually connected to the touch panel. Thus, when the actual number of connection lines between the touch panel and the touch panel controller is less than L or K, a waveform that corresponds to an arbitrary drive signal line of the non-connected drive signal lines may be used.

According to the above configuration, the touch pen is configured of an electronic pen that outputs a quantitative characteristic value such as a pen pressure level.

In the present invention, the electronic pen produces output that indicates that the quantitative characteristic value of the electronic pen is increased from the characteristic value of the previous output by using the waveform that corresponds to the (L+1)-th drive signal line and, meanwhile, produces output that indicates that the quantitative characteristic value of the electronic pen is decreased from the characteristic value of the previous output by using the waveform that corresponds to the (L+2)-th drive signal line. The touch panel controller is provided with the conversion output unit that converts and outputs the quantitative characteristic value by using the sum of the initial value of the quantitative characteristic value and the number of output × the unit amount of increase or decrease in the waveform that corresponds to the (L+1)-th drive signal line or in the waveform that corresponds to the (L+2)-th drive signal line.

That is, in the present invention, the electronic pen outputs only two types of information that indicates whether the quantitative characteristic value is increased or decreased from the characteristic value of the previous output.

The conversion output unit is disposed in the touch panel controller. The conversion output unit converts and outputs a quantitative characteristic value by using the sum of the initial value of the quantitative characteristic value and the number of outputs × the unit amount of increase or decrease in the waveform that corresponds to the (L+1)-th drive signal line or in the waveform that corresponds to the (L+2)-th drive signal line.

Accordingly, since only two types of signals related to increase and decrease are used even when a quantitative characteristic value that has many types of information is output, the amount of signals is small, and transmission can be performed in a short amount of time. In addition, signal processing on the reception side is simplified because it is only necessary to obtain the cumulative value of increase and decrease from the initial value of the quantitative characteristic value.

Therefore, when the electronic pen that outputs a quantitative characteristic value which has many types of information is used, it is possible to provide the touch panel system that may transmit the information simply in a short amount of time.

In the touch panel system 1 in a second aspect of the present invention, the conversion output unit 19 in the touch panel system 1 of the first aspect preferably includes the unit increase or decrease amount changing unit 19 b that changes the unit amount of increase or decrease.

When, for example, the quantitative characteristic value of the electronic pen is generated in a short amount of time, a difference occurs between the quantitative characteristic value and the actual quantitative characteristic value of the electronic pen if the unit amount of increase or decrease is not increased.

Regarding this point, in the present invention, since the conversion output unit is provided with the unit increase or decrease amount changing unit that changes the unit amount of increase or decrease, the unit increase or decrease amount changing unit can change the unit amount of increase or decrease.

Therefore, it is possible to suppress the occurrence of a difference between the quantitative characteristic value and the actual quantitative characteristic value of the electronic pen.

In the touch panel system 1 in a third aspect of the present invention, the unit increase or decrease amount changing unit 19 b in the touch panel system 1 of the second aspect preferably includes the continuous increase or decrease changing unit 19 c that increases or decreases the unit amount of increase or decrease when the continuous number of outputs in each of the waveform that corresponds to the (L+1)-th drive signal line (drive line DL_(L+1)) and the waveform that corresponds to the (L+2)-th drive signal line (drive line DL_(L+2)) is P (P is an integer greater than or equal to two).

What can be detected by the conversion output unit is only the number of outputs in a certain amount of time in the waveform that corresponds to the (L+1)-th drive signal line or in the waveform that corresponds to the (L+2)-th drive signal line. Therefore, the problem is how the unit increase or decrease amount changing unit determines whether to change the unit amount of increase or decrease.

Regarding this point, in the present invention, the continuous increase or decrease changing unit is disposed in the unit increase or decrease amount changing unit to increase or decrease the unit amount of increase or decrease when the continuous number of outputs in each of the waveform that corresponds to the (L+1)-th drive signal line and the waveform that corresponds to the (L+2)-th drive signal line is P (P is an integer greater than or equal to two).

That is, for example, when the number of continuous outputs in the waveform that corresponds to the (L+1)-th drive signal line is P (P is an integer greater than or equal to two), it is determined that a rapid change occurs, and the unit amount of increase or decrease is, for example, doubled. In addition, when, for example, increase further continues, the unit amount of increase or decrease can be further increased.

Accordingly, since the unit amount of increase or decrease can be increased even if the quantitative characteristic value of the electronic pen is generated in a short amount of time, it is possible to suppress the occurrence of a difference between the quantitative characteristic value and the actual quantitative characteristic value of the electronic pen.

In the touch panel system 1 in a fourth aspect of the present invention, the electronic pen in the touch panel system 1 of any one of the first to third aspects can include the pen pressure sensor 31 d.

Accordingly, it is possible to detect the pen pressure information that is an example of a quantitative characteristic value when the electronic pen touches the touch panel.

An electronic device (mobile phone 60) in a fifth aspect of the present invention is provided with the touch panel system 1 of any one of the first to fourth aspects.

According to the invention, it is possible to provide the electronic device that is provided with the touch panel system which may transmit information simply in a short amount of time when the electronic pen that outputs a quantitative characteristic value which has many types of information is used.

The present invention is not limited to each embodiment described above. Various modifications can be carried out within the scope of the claims. In addition, an embodiment that is obtained by appropriately combining technical means disclosed in each different embodiment is also included in the technical scope of the present invention.

INDUSTRIAL APPLICABILITY

The present invention can be used in a touch panel system and an electronic device that detect the position of a touch of a touch pen on a touch panel which has electrostatic capacitances formed at each intersection of a plurality of first signal lines and a plurality of second signal lines and as an electronic device, for example, can be used in a mobile phone.

REFERENCE SIGNS LIST

1 TOUCH PANEL SYSTEM

2 TOUCH PANEL

3 STYLUS PEN (TOUCH PEN, ELECTRONIC PEN)

10 TOUCH PANEL CONTROLLER

11 MULTIPLEXER

12 DRIVER (DRIVE UNIT)

13 SENSE AMPLIFIER (DETECTING UNIT)

14 TIMING GENERATOR

15 AD CONVERTER

16 CAPACITANCE DISTRIBUTION CALCULATING UNIT

17 TOUCH RECOGNIZING UNIT

18 PEN POSITION DETECTING UNIT

19 CONVERSION OUTPUT UNIT

19 a SUMMATION UNIT

19 b UNIT INCREASE OR DECREASE AMOUNT CHANGING UNIT

19 c CONTINUOUS INCREASE OR DECREASE CHANGING UNIT

30 PEN MAIN BODY

30 a HOLDING PORTION

31 PEN TIP PORTION

31 a PEN TIP COVER

31 b PEN TIP AXIS

31 c INSULATOR

31 d PEN PRESSURE SENSOR

32 CONNECTION SWITCH

33 CONTROLLER CIRCUIT

34 a, 34 b OPERATION CHANGING SWITCH

35 SENSE CIRCUIT (SYNCHRONIZATION SIGNAL DETECTING UNIT)

36 SYNCHRONIZATION SIGNAL DETECTOR CIRCUIT (SYNCHRONIZATION SIGNAL DETECTING UNIT)

36 a RESET CIRCUIT

37 TIMING ADJUSTER CIRCUIT

38 DRIVE CIRCUIT

39 a FIRST OPERATING SWITCH

39 b SECOND OPERATING SWITCH

60 MOBILE PHONE (ELECTRONIC DEVICE)

61 DISPLAY PANEL

62 OPERATING KEY

63 LOUDSPEAKER

64 MICROPHONE

65 CAMERA

66 CPU

67 ROM

68 RAM

69 DISPLAY CONTROLLER CIRCUIT

C11 to CKL ELECTROSTATIC CAPACITANCE

DL₁ to DL_(K) to DL_(L) DRIVE LINE (DRIVE SIGNAL LINE)

F FIXING PERIOD

HL₁ to HL_(K) HORIZONTAL SIGNAL LINE

R RESET TIMING

SL₁ to SL_(K) to SL_(L) SENSE LINE (DETECTION SIGNAL LINE)

VL₁ to VL_(K) to VL_(L) VERTICAL SIGNAL LINE 

1. A touch panel system comprising: a touch pen; a touch panel that has electrostatic capacitances formed at each intersection of K (K is an integer greater than or equal to two) numbers of first signal lines and L (L is an integer satisfying L≧K) numbers of second signal lines; and a touch panel controller, wherein the touch panel controller outputs drive signals that drive the K numbers of the first signal lines or the L numbers of the second signal lines from a drive unit through L numbers of drive signal lines and receives input of detection signals from the K numbers of the first signal lines or the L numbers of the second signal lines detected by a detecting unit through L numbers of detection signal lines on the basis of a change in charges that is accumulated in the electrostatic capacitances due to the touch pen when the touch pen touches the touch panel, the touch pen is configured of an electronic pen that outputs a quantitative characteristic value, the electronic pen produces output that indicates that the quantitative characteristic value of the electronic pen is increased from the characteristic value of a previous output by using a waveform that corresponds to an (L+1)-th drive signal line other than the L numbers of the drive signal lines and, meanwhile, produces output that indicates that the quantitative characteristic value of the electronic pen is decreased from the characteristic value of the previous output by using a waveform that corresponds to an (L+2)-th drive signal line other than the L numbers of the drive signal lines, and the touch panel controller includes a conversion output unit that converts and outputs the quantitative characteristic value by using the sum of the initial value of the quantitative characteristic value and the number of outputs × the unit amount of increase or decrease in the waveform that corresponds to the (L+1)-th drive signal line or in the waveform that corresponds to the (L+2)-th drive signal line.
 2. The touch panel system according to claim 1, wherein the conversion output unit includes a unit increase or decrease amount changing unit that changes the unit amount of increase or decrease.
 3. The touch panel system according to claim 2, wherein the unit increase or decrease amount changing unit includes a continuous increase or decrease changing unit that increases or decreases the unit amount of increase or decrease when the continuous number of outputs in each of the waveform which corresponds to the (L+1)-th drive signal line and the waveform which corresponds to the (L+2)-th drive signal line is P (P is an integer greater than or equal to two).
 4. The touch panel system according to claim 1, wherein the electronic pen includes a pen pressure sensor.
 5. An electronic device comprising: The touch panel system according to any one of claims 1 to 4 claim
 1. 